I'm not entirely sure it's just because of the microchip shortage. I think a lot of it is down to the massive drive for electric cars and any new remotely exciting petrol car is a vast sum of money (£80k for an M3) and then there's the VED to consider.
For this to be true though the price inflation would have to apply only to specialist high performance cars - but it doesn't. Even ordinary stuff is up in value by large percentage amounts.
Also, who is really paying £80k for an M3? Comedy list prices accompanied by double digit percentage discounts have become the norm now - much to the annoyance of people buying cars with a list price of about £45k...